Dielectric relaxation and ionic conductivity studies of Na2ZnP2O7

Abstract

The Na 2 ZnP 2 O 7 compound was obtained by the conventional solid-state reaction. The sample was characterized by X-ray powder diffraction, infrared analysis and electrical impedance spectroscopy. The impedance plots show semicircle arcs at different temperatures and an electrical equivalent circuit has been proposed to explain the impedance results. The circuits consist of the parallel combination of bulk resistance R p and constant phase elements CPE. Dielectric data were analyzed using complex electrical modulus M* for the sample at various temperatures. The frequency dependence of the conductivity is interpreted in terms of Jonscher's law. The conductivity σ d.c. follows the Arrhenius relation. The near value of activation energies obtained from the analysis of M″ and conductivity data confirms that the transport is through ion hopping mechanism, dominated by the motion of the Na + ions in the structure of the investigated materials.

Hydrothermally Synthesized h-MoO3 and α-MoO3 Nanocrystals: New Findings on Crystal-Structure-Dependent Charge Transport

“…From the above results, it is clear that the value of n is closer to 1 for α-MoO 3 , showing an ideal capacitive behavior, whereas the low value of n in the case of h-MoO 3 shows nonideal capacitive behavior. The nonideal capacitive behavior in h-MoO 3 can be attributed to ion migration within the crystal interior, which causes a loss of capacitance. − …”

Synthesis, Electrical Properties and Na+ Migration Pathways of Na2CuP1.5As0.5O7

“…The crystallographic study was started by a simple comparison between the XRD pattern of the prepared materials in the Na 2 O-CuO-P 2 O 5 -As 2 O 5 system and those of the previous studies of diphosphate Na 2 MP 2 O 7 [5,7,14,28,29] and Na 2 CoP 1.5 As 0.5 O 7 [15]. In this case, only the Na 2 CuP 1.5 As 0.5 O 7 diffractogram showed a similarity with that of the β-Na 2 CuP 2 O 7 diphosphate [17].…”

“…The Na 2 MP 2 O 7 systems (M = transition metal) [13,14] have a layered structure with the layers [MP 2 O 7 ] n 2n− and the sodium cations localized in the interlayer space, which favors high ionic conductivity. We recently investigated the effect of the substitution of P by As with a larger ionic radius for ionic conductivity and showed the improvement of ionic conductivity for Na 2 CoP 1.5 As 0.5 O 7 [15], which has an electrical conductivity value of σ 240 • C = 7.91×10 −5 Scm −1 and an activation energy Ea = 0.56 eV compared to Na 2 CoP 2 O 7 (σ 300 • C = 2 × 10 −5 Scm −1 ; Ea = 0.63 eV) [13].…”

Preparation, structure, surface and impedance analysis of Na2Zn0.5Mn0.5P2O7 ceramics

“…At 660 K the phase transition in the Na 2 MnP 2 O 7 compound leads to the anomalies of dielectric permittivity, electric conductivity and the change of activation energy from 0.78 eV at T ≤ 660 K to 0.68 eV at T ≥ 660 K. The authors of Ref. [17] show that relaxation processes in the polycrystalline Na 2 ZnP 2 O 7 are caused by the Na + -ion motion and their activation energy of 0.94 eV is almost the same as the activation energy for the conductivity. At 600 K the values of the conductivity were 3.7·10 -3 S/m and 4.98·10 -6 S/m for Na 2 MnP 2 O 7 [15] and Na 2 ZnP 2 O 7 [17], respectively.…”